Air conditioning system



y 1945,- R. B. P. CRAWFORD AIR CONDITIONING SYSTEM Original Filed March13, 1939 INVENTOR. 'Ro'laanfiff CraLwforL BY J A Patented July 31, 1945Robert B. 1 Crawford, Washington, D. C.

Original application March 13, 1939, Serial No. 261,487. Divided andthis application May,9, 1942, Serial No. 442,320

11 Claims.

This invention relates to an air conditioning system and while theinvention is particularly adaptable in connection with ra'ilway'car airconditioning, its principles are broadly applicable to air conditioningsystems for all types of structures. v

The invention is concerned primarily with producing cooling anddehumidifying and particularly, with maintaining air in a. space atdesirable conditions of humidity by means of expanding form of airconditioning system embodying my invention.

Figure 2 is a diagrammatic illustration of the control arrangementsapplying to the air conditioning system of Fig. 1.

Figure 3 is a cross-sectional view taken along the line 3--3 of Figure2.

compressed airand separating the moisture v therefrom. In railway carair conditioningmompressed air from the train line may conveniently beused for the purpose, the compressed air being expanded through aturbine and then having'part 'of its moisture separated out in aseparating chamber. Fresh air may be entrained with the air as it isexpanded. Also, the invention contemplates that the power produced bythe turbine be utilized to drive auxiliary equipment forming a part ofthe system. The invention also comprehends providing mechanicalrefrigeration means for performing sensible cooling of the air, themechanical refrigerating apparatus beingso controlled as to do onlysensible cooling with the humidity being maintained at the proper levelby controlling the amount of air being expanded through the turbine.

In accordance with the foregoing general precepts of my invention, itsprimary object is to provide an air conditioning system wherein humidityin a space is maintained by supplying relatively dry air which has beenexpanded through a turbine and passed through a moisture separatingchamber and maintaining the tem perature by effecting sensible coolingof the space air by means of mechanical refrigerating equipment.

Another object of the invention is to maintain temperature and humidityin a, space by passing controlled volumes of air through a turbine to beexpanded therein, separa'tingmoisture from the expanded air andmaintaining the temperaportion of a railway car illustrating a preferredThe present application is a division ofmy earlier filed application,SeriaLNo. 261,487, filed March 13, 1939, Patent No. 2,304,151, issuedDecember 8, 1942.

Referring to the drawing, an air conditioning system is shown in Figure1 which, as shown, may be located in the end portion of a railway car.

In this figure, compressedairfrom the train line or other suitablesource flows through a pipe i0 to a turbine II located beneath the car,the air driving the turbine and expanding therein and being delivered toan eliminator or separator chamber I2 provided with a series ofeliminating plates I3 for removing moisture from the air,

, The inlet of the chamber I! through which the expanded air isdelivered is provided with a suitable fresh air inlet opening I4 whichis so formed that the air discharged from the turbine II will entrainfresh air which will flow through the opening I4 and mix with theexpanded air from the turbine II.

Prior to passing to the turbine H, the compressed air in the line I0 issuitably cooled by passing through a spray from a series of spraynozzles I6, that portion of the pipe I0 located below the spray I6 beingprovided with a series of fins ll spaced closely enough together so thatwater flowing thereover will be held thereon by capillary action betweenthe fins, thus increasing the cooling effectof the water. The water tothe spray I6 is delivered from a. suitable storage tank I8 to whichwater is delivered from any suitable source and one. railroad train thewater leaving wash basins, water fountains, etc., may be delivered tothis tank l8 so that this water is put to a useful purpose. .Thecompressed airwhich has now been reduced in temperature bythe spray I6flows to the turbine ll under the control of a valve 20 operated by aproportioning motor 2| which is controlled in a manner to be laterdescribed. In order to utilize the energy given up by the compressedairin expanding in the turbine s II, the condenser 28 consisting of finnedtubes and the pipe 2| having separate nozzles so that the condensate isseparated over the rlnned tubes. The air leaving the turbine II, whichon expending to atmospheric pressure has its temperature greatly reducedto a value belowits 'dew-' point, will produce av flne log ormist in thechamber I! when mixed with humid air entering at H. and this air whichis mixed with the fresh unconditioned air has this moisture removed bymeans of the eliminator plates I I and the combination of the expandedair having a low dewpoint with the fresh unconditioned air will producea mixture of air having a low relative humidity.- This air passesthrougha passage-way, 21 within the rear compartment which. leadsto an outletopening 28 communicating with another passageway 29 which may be locatedwithin the root or the car and extending longitudinally thercoi'andprovided with suitable downwardly to'tbe compressor and motor 40 andwhen-the switch arms 68 and 81 are in engagement with 1 directedopenings ill by means of which theair passes to the passenger space ofthe car. Return air is circulated through a path including the passengerspree, rear compartment and chamber 2| of said carand mixed in thechamber 29 with the fresh conditioned air by means of a fan 3| a rise insuction pressure to a predetermined value the bellows 55 will expand andmove the arm 81 back into engagement with the contact ll. The arms I53and 51 are normally biased in a clockwise direction by coil springs asshown.

Th battery as is provided for supplying power their respective contacts,power is supplied to the motor 40 as follows: from one side at battery28 through conductors II and ti, arm 88, contact 52, conductor armjl,contact 58, conductorv 15, motor and conductors I and I! back to theother side oi th'e battery 28. Accordingly,- it will be seenthat thecompressor is placed in, over,

.-ation whenevcrfthe suction pressure is above a predetermined .valueand the bead pressure is bea low a predetermined value. But should thehead pressure becomehigh enough or the suction pressure become lowenough the circuit .to the compressor motor will be. interrupted and-thecomlocated within a chamber 32 which has outlets I3 air outlet 2! sothat the air will be properly mixed with the fresh conditioned air. Thechamber 82 has inlets 33 and "a which may be located. in

, the rear compartment oi." the carvand the vestibule respectively anddampers 35 suitably interconnected by adjusting mechanism 36 are pro-1vided for regulating the flow 01' air through these i -and 84 locatedabove and below the conditioned adjusted and are so arranged-that bothdampers will be simultaneously opened'or closed.

Located within the chamber 82 i a cooling coil 38 which is provided iorremoving sensible heat only from the recirculated-air and this coolingcoil iorms the evaporator. 01' a mechanical refrigerating'system whichincludes a compressor 39. driven by a motor i l. The high pressure sideoi the compressor'coin'municates by means or. a pipe compressed air topressor will stop operating. The suction pressure controller will be setat such a value as, io'r'exainpie, so lbs. to lbs.', that during normaloperation of the system the temperature of evaporator" willnot becomelow enough to cause condensation of moisture thereon as it is intendedthat the evaporator eiiect only sensible cooling 0! the air,

but will be between 55 1". and It, for example. 1

.The condenser "is preierably'so located the spray'ifi wilialso cool thecondenser in the sameway as it does the'pipe' it which carries vice ll.

- ualswitches may be provided if desired for interrupting operation orthe'ian SI and the compresscdmotor 40 whenever desired. a I

.The now oi refrigerant through the cooling 0011,38 is controlled by anexpansion valve 11,

ll with condenser 25 which in turn communicates by means or pipe 42withfithe inlet oithe evaporator ll. The outletiot the evaporator communicates with the inlet or the compressorby this expansion valve beinga thermostatic type having suitable means for varying the s'uperheatsetting thereof. The construction or thls'expa'nsion valve forms no partof the presentinvention means of the pipe- 49. The operation of'theccmpressor as illustrated is controlled by {a device responsive to thepressure .onthje high pressure i side of the system and a deviceresponsive to the I pressure on the lcwpressure oi -the; s'ystem. Forthis W; a. bellows-t ,il isaconnected by means oi'a pi e on with onepipe connected to the high pressure side or the compressor, and thebellows ll controls the Position bran II which cooperates with a fixedelectrical contact P i'i jected to a pressure corresponding to thetemperbut'maybeconstructed as illustrated in Patent No. 2,019,724,issued November 5, 1935.10 C. A.

Otto. Such an expansion valve comprises. an operating-diaphram orbellows iorming a pair 01' chamb'era'one or which is connected to a bulbI! y means-oi a capillary ll, this-bulb being "provided with a suitablevolatile iill and being positioned in contact with the outlet oi theevapit. The arrangement is; such that as the head pressure on thecompressor rises to a suincientiy high value the bellows ll'willexpandand move the arm I! out of engagement with the contact I:

and upon a drop in thehead'pres sureto apr n termined value, the bellowswill contact-and'the arm II will move back into. 1 contact. It. A secondbellows II -is such that upon adrop in suction'pressure'to a predetermind v ue. the "or the beitiled electrical contact Illiei. u

orator so that one oi the chambers will be sub- .ature or therefrigerant leaving the evaporator;

(The details or the 'expansionlvalve mechanism may. bemore fullyunderstood by inspecting Elgure 2.) The. other or the said chambers issubiccted-to' the pressure of the refrigerant in the evaporator so thatthe operating diaphragm or ,bcllows moves in accordancewith variationsin"the superheat oi the refrigerant at the outlet of evaporator. v o bymemo! a spring ll (see Ike hrs 2) The. valve: is biased towards and thetension oi'the spring may be adiust'edb'y means of a propcrtionina motorll so that the valve is adjusted to maintain varying degrees oisuper-heat which has-the cases I m. v

the turbine or espansion dethe battery 91.

ing the effective cooling surface of the evaporator. The adjustment ofthis spring by the motor 8| is controlled by a thermostat 82, whichthermostat is shown as comprising a bulb 83 located in the return airinlet duct 34a, this bulb being connected by means of a capillary tube84 with the bellows 85 which controls the position of a slider arm 86with respect to a potentiometer resistance 81. (Figure 2.) As thetemperature of the air in the car or the air entering the inlet 34aincreases, the bellows 85 will expand and move the arm 86 to the rightwith respect to the lished between the evaporator coil and the member 9|which will energize a relay 92. This relay comprises a winding 93, andan armature 94 connected to a switch blade 95 which cooperates withfixed electrical contacts 96 and 91, the armature moving the blade 95 sothat it engages contact 96 when the relay is energized and so that-itengages the contact 91 when the relay is deenergized. A battery 91' maybe provided to supply power to the relay 92 or any other suitablesources of power may be employed. As soon as condensation forms on theevaporator and a circuit between the evaporator coil 38 and the member9| is completed by the moisture thereon,

relay winding 93 will be energized as follows: from the battery 9'!through conductor 98, evaporator coil 38, member 9|, conductor 99,winding 93, and conductor I08 back to the other side of Energization ofthe relay causes arm 95 to move into engagement with contact 96 asdescribed above.

The member 9| may be compos'edpf a sheet of perforated material woundaround .the pipe and clamped together by means of a clamping screw asshown in Figure 3. The spacer members 9|] are separated as shown inFigure 3 to permit an upward flow between the evaporator coil and themember 9| so that evaporation of moisture which condenses on theevaporator coil may be rapidly effected, the perforations in the member9| permitting that portion of the evaporator coil surrounded thereby tobe contacted by the air passing through the chamber 32. Y

When the relay 92 is energized by reason of I condensation of moistureon the evaporator indicating that the evaporator is removing latenttionpressure on the compressor will rapidly decrease so that the compressorwill shut down. Until the temperature in the evaporator rises suffciently so that the, moisture on the evaporator 76 coil has beenevaporated, the expansion valve will remain closed so that there will beno further cooling thereby. As' soon as the moisture on the evaporatorcoil has evaporated however, the circuit to the relay 92 will beinterrupted and the arm 95 will move into-engagement with the contact91. The center terminal of the motor 8| will nOw be connected to thecontrol arm 86 of the temperature responsive device 82 as follows: fromthe center terminal of the motor through conductor I05, arm 95, contact91, and conductor I08 to the arm 86. The right hand end of theresistance 81 is connected by means of the conductor I09 to the righthand terminal of the motor 8| and the other end of the resistance 81 isconnected by means of conductors H6 and H11 to the left hand terminal ofthe motor 8|. It will accordingly be apparent that the motor 8| willoperate in accordance with the temperature at the bulb 83 and as thetemperature increases the motor will operate to adjust the setting onthe spring 89 so that the expansion valve will maintain the refrigerantat the evaporator outlet at a lower degree of superheat so that agreaterportion of the evaporator coil will be effective and more cooling willbe pro duced thereby. Conversely, upon a decrease in temperature of theair entering the inlet 34a the spring of the expansion valve will beadjusted so that a higher degree of superheat of the refrigerant at theevaporator outlet will be maintained and a smaller area of the coil willbe effective for cooling purposes and the temperature of the air passingthereover will be reduced to a lesser extent. It will be apparent thatwhen the relay 92 is energized by reason of condensation on theevaporator, the movement of arm 95 out of engagement with contact 91interrupts the circuit to the control arm 86 so that the thermostat hasno control whatever over the position of the expansion valve.

For controlling the operation of the valve 28 which regulates the flowof compressed air from the pipe l0 through the turbine is a humidityresponsive device .I H? which responds to the humidity of the airpassing from the rear compart ment of the car through the return airinlet opening 34a. The humidity responsive device comprises a humidityresponsive element 6 which, controls the position of a slider arm II!with respect to a potentiometer resistance 8, the slider and resistancecooperating to control the motor 2| which positions the valve 20. Uponan increase in humidity of the air in the space being conditioned, or ofthe air passing through the return air inlet 34a, the slider arm ||1will move to the right over the resistance H8 and cause the motor 2| tomove the valve 28 towards open position by an amount which isproportional to the increase in humidity. As the amount of compressedair to the turbine H is increased, there will be a greater amount ofcooled air with a low dew-point admitted to the chamber' l2 andaccordingly mixed with the cooled return air from the chamber 32 whichwill have the effect of reducing the relative humidity in the spacebeing conditioned. This humidity responsive device may operate to movethe valve from a fully closed positionto a fully 01 "ned position as thehumidity in the space increases from 45% to 55% ior example.

It will now be understood that accordingto the invention, the humidityin the space is controlled by controlling the supply of compressed airto the turbine and as the humidity increases, the valve 28 moves fromclosed to open position.

The sensible cooling of the air in the conditioned space'is effectedmainly by the evaporator coil 38 of the refrigeration system whichreduces the temperature of the recirculated air but which is controlledso that it does not effect any latent cooling of the airin theconditioned space so that the load on the refrigeration system is keptat a minimum. In order to secure this result the compressor is operatedto maintain the suction pressure between values of 50 pounds to 65pounds, for example, assuming a refrigerant such as Freon or F12 isutilized which will maintain the coil temperature between values such as55 F. and 70 F'., and by maintaining the suction pressure between theselimits, under normal circum stances no moisture will condense on theevaporator coils. Should there be such condensation of moisture,however, indicatin that the refrigcrating system is effecting somelatent cooling, the device 9! operates to energize the relay 92 whichcloses the expansion valve. Normally, however, the expansion valve iscontrolled in accordance with the temperature in the condensed space andthis valve is adjusted to maintain a maximum superheat when thetemperature in the space is 75, for example, and to reduce the superheatas the temperature increases so that at 80, for example, the amount ofsuperheat will be at a minimum. Accordingly, substantially all of thesensible cooling of the air is effected by the refrigeration system athigh efficiency and the latent cooling is effected by the compressed airof the expansion system, and the energy given up by the compressed airinthe expanding thereof is utilized for driviri 'g the generator 22 tocharge the battery 23 which furnishes energy for the compressor drivinggmotor and the fan motor. This may be augmented by another source ofpower if necessary. J

While a preferred form of the air conditioning system embodying myinvention has been illustrated, particularly in connection with railwaycars and the. like, it should be understood that the system disclosed isapplicable in general to air conditioning systems for all types ofstructures.

Having described a preferred form or my invention, it should beunderstood that various modifications may become apparent to thoseskilled in the art and such modifications will fall within the realm andscope of the invention. The invention is to be limited therefore, onlyin accordance with the scope of the claims appended hereto.

I claim as my invention:

1. In an air conditioning system for a railway mechanical refrigerationsystem having an evaporator for cooling such air and control meanstherefor operative to maintain said evaporator at a temperaturesufficientl high normally to pre- I vent removal of water from the aircooled by the evaporator, said dehumidified air and said cooled airbeing mixed before being used.

3. In an air conditioning system, in. combination, means fordehumidifying a first supply of air comprising means supplyingcompressed air,

' means cooling and expanding said first supply of air, means forcooling, without dehumidification, a second supply of air comprising amechanical refrigeration system including an evaporator for cooling saidsecond supply of air and control means for normally maintaining theevaporator temperature sufflciently high to prevent dehumidification ofsaid second supply of air, and means for mixing said first and secondsupplies of air and delivering such mixture to a desired point of use.

4. In an air conditioning system, in combination, means fordehumidifying a first supply of air comprising means supplyingcompressed air, means cooling and expanding said first supply of air,means for cooling, substantially without dehumidification, a secondsupply of air comprising a mechanical refrigeration system including anevaporator for cooling said second supply of air, control means fornormally maintaining the evaporator temperature sufiiciently high toprevent dehumidification of said second supply of air and meansresponsive to the actual production of condensate by said evaporator forpermitting said evaporator temperature to increase, and means for mixingsaid first and second supplies of air and delivering such mixture to adesired point of use.

5. In a system for cooling air, in combination, a mechanicalrefrigeration system including an evaporator over which the air ispassed for cooling the air, and means responsive to the actual car,means utilizing compressed air from the train line for causing a flow offresh air into the car, means for expanding the compressed air to removelatent heat therefrom, means for causing sensible cooling of the air inthe car, aid means including an evaporator of a mechanical refrigerationsystem over which the air is circulated, the condenser of therefrigeration system being provided with a plurality of closely spacedfins, means for supplying waste water from the raily car to said fins toincrease the cooling capacity thereof, and means utilizing the sameWaste water for cooling the compressed air before it is delivered to theexpanding means.

2. In an air conditioning system for a space, in combination, means tosupply dehumidified air to said space including means supplyingcompressed air, means cooling and expanding such air, and

means for supplyi cooled air to said space without removing moisturefrom such air including a 76 collection of moisture on said evaporatorfor permitting the temperature of said evaporator to rise until such,moisture has been evaporated.

6. In a system for cooling air, in combination, a mechanicalrefrigeration system including an evaporator over which the air ispassed for cooling the air, 'means responsive to a condition of therefrigerant in the system operative normally to prevent the temperatureof said evaporator from falling below a value at which moisture isremoved from the air passing over the evaporator, and additional meansresponsive to the actual collection of moisture on said evaporator forpermitting the temperature of the evaporator to rise until such moisturehas been removed.

7. A method of conditioning the air in a space which comprises coolingcompressed air, expanding the cooled compressed air, removing moisturefrom the expanded air, entraining fresh air with the expanded air anddelivering the mixture to the space, recirculating air through a pathincluding the space, cooling the recirculated air in a portion of saidpath by,removing sensible heat from the air without removing latent heattherefrom, controlling the sensible cooling of the recirculated air inresponse to the temperature of the air in a portion of said path, andcontrolling the amount of compressed air which is expanded and deliveredto the space in response to the humidity of the air in a portion of saidpath.

' 8. In an air conditioning system for a space, a source of compressedair, an expanding means, means for directing said compressed air to saidmay be expanded and cooled, means for cooling the compressed air passingto the expanding expanding means wherein the compressed air may beexpanded and cooled, means for cooling the compressed air passing to theexpanding means, means for removing moisture from the expanded air,means for entraining fresh unconditioned air with the air leaving saidexpanding means and delivering the mixture of fresh and cooled air tothe space, means for recirculating air through a path including thespace, a sensible coolin means, means for directing said recirculatingair over said sensible cooling means, means responsive to thetemperature of the air in a portion of said path controlling saidsensible cooling. means, and

, means, means for removing moisture from the exmeans responsive to thehumidity of the air in a portion of said path controlling the flow ofair to the expanding means.

9. In an air conditioning system for a space, a source of compressedair, an expanding means, means for directing said compressed air to saidexpanding means wherein the compressed air may be expanded and cooled,means for cooling the compressed air passing to the expanding means,

means for removing moisture from the expanded air, means for entrainingfresh unconditioned air with the air leaving said expanding means anddelivering the mixture of fresh and cooled air to the space, means forrecirculating air through a path including said space, a sensiblecooling means, means for directing said recirculating air over saidsensible cooling means, said sensible cooling means comprising anevaporator of a direct expansion refrigerating system, means responsiveto the temperature of the air in a por- Y tion of said path forcontrolling the flow of refrigerant through said evaporator, and meansresponsive to the humidity of the air in a portion of the path forcontrolling the flow of air to the expanding means.

10. In an air conditioning system for a space, a source of compressedair, an expanding means, means for directing said compressed air to saidexpanding means wherein the compressed air panded air, means forentraining fresh unconditioned air with the air leaving said means anddelivering the mixture of fresh and cooled air to the space, means forrecirculating air through a path including said space, a sensiblecooling means, means for directing said recirculating air over saidsensible cooling means, said sensible cooling means comprising anevaporator Of a direct expansion refrigerating system,

means responsive to the humidity of the air in a I portion of said pathfor controlling the flow of air to the expanding means, and meansresponsive to the condensation of moisture on said evaporator coil forinterrupting the flow of refri erant therethrough.

11. In an air conditioning system for a railway car space, meansutilizing compressed air from the train line for causing a flow of freshair into the space, means for expanding the compressed air to removelatent heat therefrom, means for circulating other air in-a flow pathincluding said space, means for causing sensible cooling of said otherair, said means including an evaporator of a mechanical refrigeratingsystem over which said other air is circulated, the condenser of therefrigerating system being provided with a plurality of closely spacedfins, means for supplying waste water from the railway car to said finsto increase thecooling capacity therefor, said waste water also beingused to cool said compressed air before the same is expanded, meansresponsive to the humidity of the air in a portion of said flow path forcontrolling the supply of compressed air to the expanding means, andmeans responsive to the temperature of the air in a portion of said flowpath in control of the flow of refrigerant 40 through said evaporator.

expanding 1

